Dickson



Feb. 21, 1956 J. DICKSON 2,735,313

FOLLOWER Filed April 22, 1950 3nnentor (Ittornegs United States Patent FOLLOWER John Dickson, Huntington Woods, Mich assignor to General Motors Corporation, Detroit, M1ch., a corporation of Delaware Application April 22, 1950, Serial No. 157,611

Claims. (Cl. 74-569) The invention relates to internal combustion engines and particularly to cam and follower mechanisms for operating valves, fuel injection devices, etc. in such engines.

One object of the invention is to provide an improved cam follower of light weight and economical construction comprising an assemblage of three members in series thrust transmitting relation, the intermediate member being in the form of an elongated rod and the end members being in the form of cups receiving and laterally supporting the respective ends of the rod.

Another object of the invention is to provide a cam and roller follower mechanism wherein the roller is provided with a bore bellmouthed at opposite ends to accommodate deflection of its journaling member during the cam lift stroke, and the rolling contact surfaces of the cam and roller are crowned to accommodate axial misalignment between the roller and the cam.

The means by which these and other objects of the invention are attained will be better understood from a reading of the following description, having reference to the drawings wherein:

Figure l is an elevational sectional view of a portion of an internal combustion engine showing my improved cam and follower mechanism associated therein for operating a fuel injection pump.

Figure 2 is an enlarged view taken in section on line 2-2 of Figure 1.

Referring now to the drawing, the numeral 1 designates generally the frame of an internal combustion engine having a cylinder head 2, cylinder casing 3 and plunger-type fuel injector pump 4. The plunger 6 of the pump is arranged to be reciprocated by the engine camshaft 7 through a roller follower -mechanism 8, upper push rod 10 and rocker 11.

The follower 8 comprises a lower push rod 9, the lower end of which abuts and sockets in the end wall of a cup-shaped member 12 which is slidably reciprocable in the bore 13 of a bushing fixed in the engine casing 3. The lower end of the upper push rod 10 similarly abuts the end wall of an inverted cup member 14 which, in turn, socketably receives and abuts the upper end of the lower push rod 9, and is similarly slidably reciprocable in the bore 13.

The lower end of the cup-shaped member 12 terminates in a pair of spaced-apart depending arms 21 and 22 which support the respective ends of a roller shaft 20. The shaft 20 is preferably cylindrical throughout its length and is retained end-wise by spun-over lips 23 and 24 integral with the arms 21 and 22.

The roller 30, which may be formed as one piece, or of separate rim and bushing portions 31 and 32, is adapted to rotate about the shaft 20 and to be guided endwise thereof by the inner faces of the arms 21 and 22. The bore of the roller or of its bushing 32 has a section 35 intermediately of its length freely fitting the cylindrical surface of the shaft 20, and toward each ice end thereof from the section 35 the bore is bellmouthed as shown at 36 and 37.

When the cam causes load to be transmitted through the roller 42 to the shaft 20, it will deflect as a beam supported by the arms 21 and 22. If the bushing 32 is made with parallel bore, then the outside bearing surface of bushing 32 will be subjected to high concentration of load, causing possible destruction of the oil film with subsequent damage to bearing and shaft. By making the bushing bellmouthed giving the bushing a curvature similar to that of the deflected shaft under maximum load, then a distribution of load on the oil film results. The greater the load, the greater the shaft deflection, with resulting greater distribution of the load over the bearing surface. The action of the shaft as it deflects in the bellmouthed bearing is that of an oil pump, oil being drawn in and pumped out during each period of unloading and loading.

The cam 40 on the camshaft 7 has its follower lifting surface crowned as shown at 41, and the peripheral external surface of the roller 30 is similarly crowned as shown at 42. The crowning of these surfaces allows the roller and cam to have unrestrained rolling engagement with each other during cocking of the roller about its shaft 20.

The upper push rod 10 has a pivotal connection at 15 to the rocker 11 and is biased toward the camshaft at all times by a compression spring 16, the upper and lower ends of which are retained by washers abutting the cylinder head at the shoulder 17 and the conical shoulder 18 on the upper rod 10.

I claim:

1. ln a cam and follower mechanism, a rotary cam having a crowned follower lifting surface, a follower having a reciprocably guided portion terminating in a bifurcation opposite the cam surface, a shaft extending through said bifurcation and supported on each side thereof by said portion, and a roller rotatable about the shaft within said bifurcation, said roller having a crowned periphery in rolling engagement with the cam surface and a bore bellmouthed at each end and journaling intermediately of its ends on the shaft.

2. In a cam and follower mechanism, a rotary cam operating surface, a follower provided with a roller having a peripheral surface in rolling engagement with the cam surface, one of said surfaces being crowned, a shaft supported at opposite ends of the roller by the follower, said roller having a bore bellmouthed at opposite ends and journaling the roller on the shaft intermediate the ends of the bore.

3. In a cam and follower mechanism, a rotary cam having a crowned follower lifting surface, a follower having a reciprocably guided portion opposite the cam surface, a shaft carried by said portion, and a roller having a crowned cam contacting surface and a bellmouthed bore journaled by the shaft.

4. In a cam and follower mechanism, a rotary cam, a reciprocably guided follower therefor including a roller in rolling engagement with the cam and a shaft 1'0- tatably supporting the roller, said shaft having a cylindrical portion constituting the journal for the roller, said roller having a bore bellmouthed at each end and journalling intermediately of its ends directly on said shaft cylindrical portion.

5. A roller follower comprising a roller having a central bore the diameter of which increases at a progressive rate in opposite directions from the bore midsection, and means rotatably supporting said roller including a yoke having arms embracing opposite sides of the roller and a shaft radially supported by each of said arms, said shaft having a cylindrical portion intermediate said arms directly journalling said bore mid-section.

6. A roller follower comprising a member having spaced apart arms, a shaft radially supported by each of said arms and providing a bearing therebetween for a roller, a roller thrustably guided endwise of said shaft by said arms and provided With a bore having a section radially journalling on said bearing intermediate the ends of the bore, said bore and bearing having their opposed surfaces divergent to each other on longitudinally opposite sides of said section.

7. In a cam operated linkage for the charging means of an internal combustion engine or the like, a cam follower comprising two generally cup-shaped reciprocably guided members having their respective open ends opposite and spaced from each other, fixed guide means slidably embracing and laterally supporting said members and a thrust transmitting rod terminating at its opposite ends within the cup-shaped members and socketably abutting the respective closed ends thereof, said rod being laterally unsupported intermediate said closed ends. I

8. In a cam operated linkage for the charging means of an internal combustion engine or the like, a first push rod, a fixed bushing having walls longitudinally embracing and laterally spaced from said first rod, cups slidably fitting said bushing walls and having their closed ends laterally supporting and abutting the opposite ends of said first push rod, said first push rod being laterally unsupported intermediate its said ends, one of said cups carrying a cam roller adapted to engage an operating cam, a second push rod in series thrust transmitting relation with said first push rod and having one of its ends laterally supported by and in abutment with the other of said cups and its other end adapted to engage a rocker arm.

9. In an articulated cam follower means, a cam engaging roller, a shaft radially supporting the roller, a bifurcated portion embracing the roller and supporting the shaft on opposite sides of the roller, said roller having a bore journaled by the shaft, said bore being bellmouthed at both ends to accommodate deflection of the shaft under bending loads imposed by the roller, said bifurcated portion terminating at its end remote from 4 v v a the roller in a cup-shaped portion guided for axial reciprocation toward and away from the cam, a first push rod having one end socketed within said cup-shaped portion and its opposite end extending longitudinally outward therefrom, a second push rod in series with the first push rod, and a member in direct thrust transmitting engagement with the adjacent ends of the push rods, said member being socketed in one of said adjacent ends and socketably receiving the other of said adjacent ends, said member being guided for reciprocation in alignment with said cup-shaped portion.

10. In a cam operated linkage for the charging means of an internal combustion engine or the like, a cam follower comprising two longitudinally spaced, generally cup-shaped, reciprocably guided members each having side walls and an end wall, a fixed bushing slidably embracing and reciprocably guiding the side walls of said members and a rod in series thrust transmitting relation between said members, said .rod having its 0; posite ends socketably abutting the said end walls of the respective members, said rod being laterally ,unsupported between said-end walls.

References Cited in the file of this patent UNITED STATES PATENTS 178,441 Houghtaling June 6, 1876 1,061,700 Steinberger May 13, 1913 1,471,831 Corset Oct. 23, 1923 1,658,318 Wineman Feb. 7, 1928 1,802,330 Boland Apr. 28, 193 1 1,931,691 Goldberg Oct. 24, 1933 2,081,390 Trapp May 25, 1937 2,151,832 Bugatti Mar. 28, 1939 2,445,493 Priest July 20, 1948 2,481,812 Beatrice Sept. 13, 1949 2,484,926 Bennett Oct. 18, 1949 2,515,347 Jameson July 18, 1950 2,573,506 Stokes Oct. 30, 1951 2,678,641 Ryder May 18, 1 954 FOREIGN PATENTS 26,943 Sweden May 29, 1909 911,367 France -Ma.r. 11, 1946 

